14 MASS. EXPERIMENT STATION BULLETIN 376 



rooted at 52°-55° F. for 38 days before being grown at 62°-65° F. Plants 

 from bulbs rooted at lower temperatures had much shorter internodes 

 than those from bulbs rooted at higher temperatures. 



The Howardi lily bulbs averaged only 3.2 and 2.7 blooms per plant 

 which is too low a production for profitable forcing. A larger nuinber 

 of blooms was obtained from the bulbs which were rooted at 52°-55° F. 

 However, the time required for flowering, figured from the potting dates, 

 was 23 days longer for bulbs rooted at 52°-55° F. than for bulbs rooted 

 at 62°-65° F. 



Table 5.— Effects of Rooting Temperatures on Lilium erabu 



Howard 



Effect of Artificial Light on the Flowering of Easter Lilies 



The use of artificial illumination as a means of supplying additional 

 light to growing plants has been extensively studied. In general, the 

 practice of illuminating plants with electric lamps is a supplementary aid 

 rather than a cultural method. Whether or not additional light can be 

 profitably applied to a flower crop depends upon the natural response of 

 the plants to such treatment and the cost of light application. 



Flowering and growth of lily plants can be stimulated by tlie applica- 

 tion of additional light as well as by the use of increased temperature. 

 Laurie and Poesch (7) observed that six hours of additional light from 

 150-watt electric lamps were approximately equivalent to 70° forcing 

 temperature and had ultimately the same effect. The cost of additional 

 illumination was reported as 3 to 4 cents per pot. Their recommenda- 

 tions are that light treatments be applied for 36 days to 2 montliN prior 

 to intended market date. 



In addition to the direct effect of light itself, other factors wliich cause 

 plants to vary in their response to light treatments are: first, the inherent 

 peculiarities of the plant itself; second, the length of day (photoperiod) ; 

 third, the intensity of the light; fourth, the stage of growth at the time 

 light is applied; and lastly, the temperature at which the plants are grown. 



In their studies on supplementary illumination of Easter lily plants (L. 

 longiflorum gigantcum), Greene, Withrow and Richman (1) in Indiana ap- 

 plied light and observed that th-e plants flowered earliest when irradiated 

 for 20 days, starting 16 days after the bulbs were planted. Tliese bulbs 

 were planted December 15 and lighted with 500-watt lamps for a period 

 of 5 hours each night under cultural temperatures of 65° F. at nialit and 

 70° F. during the day. The greatest decrease in number of days to flow- 

 ering noted with 500-watt lamps was 8 days. Withrow (15) in later 

 work recommends that at least 30 foot-candles or 200 watts of lialit lie 

 applied to lilies to liastcn flowering. 



